College of the Environment and Ecology, Xiamen University, Xiamen 361102, China.
Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
Water Res. 2021 Feb 15;190:116744. doi: 10.1016/j.watres.2020.116744. Epub 2020 Dec 15.
Biological activated carbon (BAC) filtration, a process widely used in drinking water treatment, was recently reported to harbor antibiotic resistance genes (ARGs). This emerging contamination is poorly understood. This study was conducted to investigate the occurrence of ARGs and bacterial community in full-scale BAC filters during the backwash cycle using high-throughput qPCR and high-throughput sequencing. A total of 178 ARGs were detected in all biofilm samples, with relative abundance ranging from 0.1 to 1.37 copies per 16S rRNA and absolute abundance ranging from 4.48 × 10 to 3.09 × 10 copies/g carbon. Biofilms sampled from different filters shared most detected ARGs and dominant genera including Bryobacter, Pedomicrobium, Reyranella, and Terrimonas, though their bacterial community structure differed significantly. After backwashing, the relative ARGs abundance increased by 1.5- to 3.8-folds and the absolute ARGs abundance increased by 0.90- to 1.12-logs in all biofilm samples during filter ripening, indicating that ARGs accumulated in filters during this period. Redundancy analysis suggested that such ARGs accumulation was mainly driven by horizontal gene transfer in winter, but highly correlated with the increasing relative abundance of genera Bryobacter and Acidibacter in summer. It was observed that 80.6 %-89.3% of the detected ARGs persisted in the filters despite of the backwashing. Given the high richness and relative abundance of ARGs in BAC filter and the ineffectiveness of backwashing in ARG removal, more stringent downstream disinfection strategies are deserved and more research is necessary to assess potential human health risks due to the persistence of ARGs in drinking water.
生物活性炭（BAC）过滤是一种广泛应用于饮用水处理的工艺，最近有报道称其存在抗生素抗性基因（ARGs）。这种新出现的污染现象尚未得到充分了解。本研究采用高通量 qPCR 和高通量测序技术，在反冲洗周期内调查了全规模 BAC 过滤器中 ARGs 和细菌群落的发生情况。在所有生物膜样本中，共检测到 178 种 ARGs，相对丰度范围为 16S rRNA 的 0.1 至 1.37 拷贝，绝对丰度范围为 4.48×10至 3.09×10 拷贝/g 碳。尽管不同过滤器采集的生物膜样本的细菌群落结构存在显著差异，但它们共享了大多数检测到的 ARGs 和主要属，包括 Bryobacter、Pedomicrobium、Reyranella 和 Terrimonas。反冲洗后，在所有生物膜样本中，ARGs 的相对丰度增加了 1.5 至 3.8 倍，绝对丰度增加了 0.90 至 1.12 个对数，表明在此期间 ARGs 在过滤器中积累。冗余分析表明，这种 ARGs 积累主要是由冬季的水平基因转移驱动的，但与夏季 Bryobacter 和 Acidibacter 相对丰度的增加高度相关。研究发现，尽管进行了反冲洗，但仍有 80.6%-89.3%的检测到的 ARGs 能在过滤器中存在。鉴于 BAC 过滤器中 ARGs 的丰富度和相对丰度较高，且反冲洗在去除 ARGs 方面效果不佳，应采取更严格的下游消毒策略，并需要进行更多的研究以评估由于 ARGs 在饮用水中持续存在而对人类健康造成的潜在风险。
